Seat assembly with movable seat and backrest and method

ABSTRACT

A seat assembly ( 21 ) for a vehicle including a seat ( 22 ), a seat mounting assembly ( 20 ) mounting the seat ( 22 ) for movement along an upwardly concaved arcuate path, a backrest ( 25 ) assembly with a backrest member ( 23 ) having a lower portion ( 18 ) coupled for arcuate motion with the seat ( 22 ) and an upper portion mounted for movement in a vertically extending direction. The backrest assembly ( 25 ) further includes a recliner frame and mechanism ( 32, 33 ). A method of providing a seat assembly also is disclosed including the steps of mounting the seat ( 22 ) for movement along an upwardly arcuate path, mounting the backrest ( 25 ) proximate the seat, coupling a lower portion ( 18 ) of the backrest for movement with the seat ( 22 ) and mounting the upper portion of the backrest ( 23 ) for vertically extending movement.

TECHNICAL FIELD

The present invention relates, in general, to seat assemblies for land,air and water vehicles, as well as stationary seat assemblies, and moreparticularly, relates to seat assemblies and methods for providing thesame in which there is a moveable seat and movable backrest.

BACKGROUND ART

Considerable effort has been directed toward improvement of the safetyof seat assemblies which are employed in various types of vehicles andthe comfort of seat assemblies which are used in vehicles and instationary applications. Typical of such effort are the seat assembliesset forth in my U.S. Pat. Nos. 4,650,249; 5,244,252; 5,460,427;5,558,399 and 5,735,574. Such prior art seat assemblies have sought toimprove seating safety and comfort by designing seat motion in a mannercontrolling body posture and the forces generated in a muscular-skeletalsystem during rapid vehicle deceleration. Numerous other patents havebeen directed to the same general goals.

My U.S. Pat. No. 4,650,249, for example, discloses a seat assembly inwhich the seat is mounted to move along a concave arcuate path having acenter of rotation proximate the center of mass of the user. In U.S.Pat. Nos. 5,244,252 and 5,460,427 the movable seat moves away from alumbar support member and thereby creates a gap in the lower lumbarregion that promotes reversing of the lumbar spine. In my U.S. Pat. No.5,735,574 the lumbar support member has been added which is linked formovement with the seat. The backrest in this patent, however, is fixed,and the lumbar support member moves up and down inside the backrestframe separating the lower part of the backrest between the upper edgeof the lumbar and backrest frame. In U.S. Pat. Nos. 5,558,399 and5,735,574, the FIG. 3 embodiment of these patents includes seat motionwhich is arcuate in a downward direction, which is undesirable from thesafety standpoint.

In addition to my above-noted prior patents U.S. Pat. No. 6,030,043 toHabedank and U.S. Pat. No. 5,961,073 to Whitmann disclose seatassemblies suitable for use in motor vehicles which include movableslots. Thus, the patent to Habedank discloses a seat which is pivoted tothe seat base at an adjustable pivot location. The backrest isindependently tiltable and also coupled to the seat so that the backrestwill be automatically tilted as the seat moves backward and forward, asdriven by an electric motor drive. The design is particularly wellsuited for use in the back seat of an automobile.

The patent to Whitmann, U.S. Pat. No. 5,961,073 discloses a seatassembly for aircrafts in which the bottom seat cushion is guided byrollers in tracks to move forward and upward upon an inertial load. Thisis combined with a lap belt to limit head excursions on crashes.

The present seat assembly and method include a seat which is mounted formovement along an upwardly concaved arcuate path having a center ofrotation proximate the center of mass of the occupant seated on theseat. This type of seat mounting is broadly known and described in myprior patents. In the present invention, however, a backrest is providedwhich also is linked or coupled for motion that is dependent upon seatmotion at the lower end and coupled by an upright slide plane supportingsaid backrest at the upper end. This linking, produces a self-adjustingeffect which realigns the seat assembly in response to changes of bodyposture by automatically and synchronously seeking equilibrium againstthe direction of gravitational acceleration and the direction of vehiclelongitudinal accelerations. In extreme cases, during frontal or rearimpact of a vehicle, the seat provides restraining safety motion toreduce injury.

The backrest frame also can be formed to recline so that the slidingmotion of the backrest can be selectively reclined. Moreover, thepresent seat assembly can work in conjunction with other restraints suchas headrests, belts, airbags, lower leg cushions and knee bolsters.Still further the seat assembly of the present invention can be adjustedand controlled to fit different sizes of users in many differentpostures, such as; an upright or slightly reclined posture for driving;a forward leaning posture for reaching controls or auxiliary equipment;a semi-reclined posture, as may be required in low vehicle cabins; andan extremely reclined seated posture, such as may be employed forsleeping in airliners or the like.

Accordingly, it is an object of the present invention to provide a seatassembly and method which provide enhanced safety and comfort forvehicular and stationary seating application.

Another object of the present invention is to provide a seat assemblyand method which provide enhanced safety for vehicle applications inwhich frontal or rear impacts rebounding accelerations and diagonallyoffset crashes can cause injurious forces.

A further object of the present invention is to provide a seat assemblyand method which can be used to provide enhanced comfort for a widevariety of seating postures.

Another object of the present invention is to provide a seat assemblyhaving improved safety and comfort which is economical to construct,durable and can be employed in a wide range of applications.

The seat assembly and method of the present invention have other objectsand features of advantage which will become apparent from, or are setforth in more detail in the accompanying drawings and descriptions ofthe Best Mode of Carrying out the Invention.

DISCLOSURE OF INVENTION

The present seat assembly comprises, briefly, a seat; a seat mountingassembly mounting the seat in a near horizontal orientation for movementalong an upwardly concaved arcuate path having a center of curvatureproximate the center of mass of a person seated on the seat; and abackrest assembly including a backrest frame extending in a nearvertical orientation proximate the seat mounting assembly and thebackrest member having an upper backrest portion mounted to the backrestframe for movement relative to the backrest frame in a near verticallyextending direction with a lower backrest portion coupled for movementwith the seat. Vertical movement of the backrest advantageously can beprovided by laterally spaced apart guide channels forming a slidingplane to which the backrest member is coupled for guided movement.Further, the backrest frame preferably includes a recliner mechanism,and optionally can include a separate or second backrest member mountedabove the coupled to the first-named backrest member for verticallyextending motion with upper portion of the first-named backrest memberrelative to the backrest frame. A vertically adjustable headrest alsomay be provided that moves with the motion of the upper end of thefirst-named backrest member.

The method of providing a seat assembly of the present invention iscomprised, briefly, of the steps of; mounting a seat in a nearhorizontal orientation for movement along an upwardly concave arcuatepath; mounting a backrest in a near vertical orientation proximate theseat for support of the back of the user while seated on the seat;coupling a lower portion of the backrest in the seat for movement of thelower portion of the backrest with movement of the seat; and mounting anupper portion of the backrest for movement in a vertically extendingdirection in response to movement of the lower portion of the backrest.

In addition when mounted in a vehicle said motion is used to reduceinjury loads to the user suffered in a frontal crash a rear-end crash ordiagonally offset impact. Also in a vehicle the present invention iscalculated to distribute the crash load bearing contribution with atleast one of a safety belt restraint, upper body airbags, knee bolsters,lower leg air bag, lower leg bolster cushion and headrest

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a top pictorial view of a seat assembly constructed inaccordance with the present invention and having a movable seat and twoconnected, movable backrest members and a movable headrest.

FIG. 2 is a side elevation view of the seat assembly of FIG. 1 mountedin a vehicle with a person seated on the seat and shown in threepositions of the range of motion of the seat and backrest assembly inconjunction with other vehicle restraints.

FIG. 3 is a side elevation view of the seat assembly of FIG. 1 with theseat assembly shown in a reclined position with the seat tilted upwardlyand backrest tilted back.

FIG. 4 is a top pictorial view of the seat assembly and seat mountingassembly of FIG. 1 with the backrest frame and backrest removed showingseat motion and control elements.

FIG. 5 is a pictorial perspective view of the underside of the seatassembly shown in FIG. 4 with the mounting assembly removed for clarity.

FIG. 6 is a bottom pictorial rear view of an alternative embodiment ofthe seat assembly of the present invention, showing a backrest frame fora single backrest member, and having a height adjustment assembly.

FIG. 7 is a side elevation view of the seat assembly of FIG. 6 shownmounted in the vehicle with the seat cushions shown over the frameworkand a person seated on the seat in solid line position while driving andin a dotted line position upon rear impact of the vehicle.

FIG. 8 is a side elevation view of further embodiments of the seatassembly as shown mounted in a vehicle, such as a van, with a seatsuspension assembly for the front seat and a rear seat installation.

FIG. 9A is a bottom pictorial view corresponding to FIG. 5 andillustrating a seat motion detent assembly and formed curved matingtracks.

FIG. 9B is an enlarged, front elevation, cross sectional view takensubstantially along the plane of line 9B-9B in FIG. 9A

FIG. 9C is an enlarged, fragmentary, side elevation view takensubstantially along the plane of line 9C-9C in FIG. 9B

FIG. 10A is a top pictorial view of an alternative embodiment of theseat assembly of the present invention showing a single backrest framemember mounted to a recliner frame to which side bolsters can also bemounted.

FIG. 10B is a top pictorial view of a two section backrest frame mountedto a recliner frame with a headrest frame mounted for movement with theupper backrest.

FIG. 10C is a rear pictorial view of a two section backrest framemounted to a recliner frame with upper backrest frame section beingfixed to the recliner frame and the headrest being mounted for movementto the lower backrest frame section.

FIG. 11 is a front elevation view of a seat assembly of the presentinvention, shown mounted on a laterally displaceable mounting assembly.

FIG. 12 is a side elevation view of a further alternative embodiment ofthe assembly of the present invention shown with an alternative seatmotion control structure.

BEST MODE OF CARRYING OUT THE INVENTION

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thepreferred embodiments of the invention, examples of which areillustrated in the accompanying drawings. While the invention will bedescribed in conjunction with the preferred embodiments, it will beunderstood that they are not intended to limit the invention to theseembodiments. On the contrary, the invention is intended to coveralternatives, modifications and equivalents, which may be includedwithin the spirit and scope of the invention, as defined by the appendedclaims.

Referring now to FIG. 1 the seat assembly of the present invention,generally designated 21, is shown in which a seat, generally designated22, is mounted by a seat mounting assembly, generally designated 20, ina near horizontal orientation for movement along an upwardly concaved,arcuate seat path having at lease one center of curvature proximate thecenter of mass of a person mounted on seat 22. Arrows 35 in FIGS. 1 and2 illustrates the upwardly concaved arcuate path of seat motion andcenter line 60 in FIGS. 1 and 2 shows the center of curvature of path 35to be located proximate a center of gravity, CG, or center of mass ofthe person seated cm the seat (FIG. 2). Construction of mountingassembly 20 to provide for movement of seat 22 along path 35 is notregarded, per se, as being novel, since such movement is clearlydisclosed in my above-referenced United States patents, which areincorporated herein by reference. FIG. 2 also shows a lower leg bolstercushion 57 that can take the form of an airbag to contribute loadbearing upon collision in a vehicle, and restraining belt anchor point74 that can be anchored to the seat mounting assembly in a positionsubstantially below, and rearward of the center of mass of the body tochange the inclined direction of a lap belt in use during a crash.Anchor 74 can take the form of a lap-belt re-route roller loop when thebelt is anchored on the floor.

Movable seat 22 may advantageously be formed with an upwardly concavedseat pan 24, as best seen in FIG. 4. Movable seat pan 24 is received byand nested in a stationary mounting assembly or shell 26. A restrainingupwardly inclined anti-submarining member 49 is advantageously providedat the front of seat pan 24. The front end of planar restraining member49 advantageously includes a lip which extends above seat pan 24 andwhich combines with the remainder of the seat pan frame to provide abucket seat support structure over which a cushion schematicallyillustrated FIG. 1 as cushion 48, extends. Restraining member 49 tendsto resist forward sliding or submarining of the person seated on theseat in the event of a frontal impact, as represented by force vector 14in FIG. 2. Restraining surface 49, therefore works in conjunction withseat motion 35 to resist submarining.

At the bottom of side walls 24 a of seat pan 24 are a pair of curveguide tracks 28 (FIGS. 1, 4 and 5) which cooperate with sliders 27 (bestseen in FIG. 5). Alternatively, roller elements (not shown) may besubstituted for sliders 27. Sliders 27 are provided by a low-frictionmaterial and can be mounted by bolts 27 a, or other fastening means, tofloor mounting members 42 (FIGS. 2 and 4), which, in turn, are carriedor fixedly mounted on fore-and-aft seat positioning tracks 40 that arecoupled to floor 45 of the vehicle. Tracks 28 can be monolithicallyformed with seat pan 24 or provided as separately attached guide tracksor channels 140, as shown in FIG. 9A.

As will be understood, therefore, arcuate tracks 28 carried by seat pan24 will cause arcuate motion of pan 24 relative to stationary sliders orglide members 27, which are fixed relative to the floor of the vehicle.It will be understood that a reversal of parts is possible in which thesliders (or rollers) are carried by the seat pan and the arcuate tracksare carried by the adjustment tracks 40 or mounting members 42 of theseat mounting assembly 20.

A seat restraining cross beam 34 (FIG. 4) prevents seat 22 fromseparating from sliders 27 and limits movement of the seat to thearcuate path of channels 28. Cross beam 34 has pads 103 mounted at eachend which pads slidably engage arcuate track 28 on the side opposite tosliders 27 to rap seat pan 24 therebetween while allowing seat movement.Cross beam 34 is held in place by face 118 of cam 102 (as best seen onunderside in FIG. 5), while being biased downwardly by compressionsprings 100. Cams 102 are fixed to a rod 104, that in turn has handle 46fixedly attached thereto. Bolts 101 hold springs 100 in FIG. 4 and thelower ends of the bolts are screwed onto brackets 111, that in turn arefixed to support means 26 shown in part in FIG. 5, with a fastener orweld).

To enable the user to selectively lock seat 22 in a desired positionagainst arcuate movement, a seat locking assembly may be provided. Theseat locking assembly can include a handle 46 which is turned to thebroken line position in FIG. 5 to position cam 102 so that lower sideface 119 of the cam is facing up. This provides clearance relative tocross beam 34 and therefore allows springs 100 to push down on frictionpads 103, which slows down or stops arcuate channels 28 relative to pads103. Arrow 116 shows the spring biasing force of the pads 103 cause byspring 100 on channels or tracks 28. Pads 103 are made of materialhaving a coefficient of friction high enough to control seat motionduring normal driving and low enough to allow seat deployment at crashimpact over known threshold (for example, a force caused by accelerationover 1-5 g).

The seat assembly of the present invention also advantageously includesa seat-femur length and lumbar depth adjuster assembly best seen in FIG.5. A rotatable adjustment device such as knob 51 is used to turn axel106 mounted to each side of the pan 24 by bushings 117. Axel 106 hasslots 107 that are formed to engage teeth 108 in a lumbar adjustmentmember or bar 109 that is slidably mounted through bracket 110 to pan 24and by guide pins 110 a (FIG. 4) which slidably rest on the top of pan24. Bar 109 provides a connection to the backrest link 50 that pivotsabout pivotal assembly 47, and thus adjustably couples the backrest tothe seat. In this manner, when knob 51 is rotated, pivot 47 and thelower or lumbar portion of the backrest 25 will move forward or back, asindicated by arrows 115. This movement adjusts the distance from thefront edge of the seat to a lower portion of the lumbar region of thebackrest frame. In effect, by controlling the length of the seat pan thedepth of the lumbar support is also controlled. As the person's pelvisis pushed fore-or-aft, the top of the pelvis rotates to increase thelumbar curve.

Seat assembly 21 also includes a backrest assembly, generally designated25, which is mounted to a backrest frame, generally designated 23. Upperbackrest frame 38 will be seen to extend in a near vertical orientationproximate seat 22, and in the present invention, a first or lowerbackrest member 36, again shown schematically in FIG. 1.

In the embodiment of FIGS. 1 and 2 there are two backrest members, lowerbackrest member 36 and a second or upper backrest member 39, while inthe embodiment of FIGS. 6 and 7, a single backrest member 36 is used.Both embodiments have a headrest member 41 mounted to the uppermostbackrest member. In FIGS. 1 and 2, headrest 41 is carried by a framemember 40 that, in turn, is mounted to upper backrest frame 38 forvertical adjustment, in a manner well known in the industry. In theembodiment of FIGS. 1 and 2 side bolsters 37 show as outline sectionalso may be mounted over the recliner frame, generally designated 32.

In the improved seat assembly of the present invention, backrest 25 iscoupled by link 50 to seat pan 24 for movement therewith. This can beaccomplished in several manners, but as illustrated in FIGS. 1 and 2, alower portion 18 of backrest frame member 23 has link 50 pivoted theretoat pivot connection 47. The lower end of link 50 is secured by bar 109,teeth 108, axle 106 and bushings 117 to seat pan 24, as described above.As seat 22 moves along fore-and-aft arcuate path, as shown by arrow 35,therefore, lower portion 18 of backrest frame 23 will follow thefore-and-aft seat motion. Link 50 can be alternatively fixed or weldeddirectly to seat pan 22.

An upper backrest portion of frame 23 is coupled by pivot member 30 to aslider member 31. Slider 31 moves in channel 29 fixedly carried bybackrest recliner frame 32 when the backrest is not reclined, it will beseen that upper portion of lower backrest frame 23 moves in a guided,vertically extending, direction as indicated by arrows 98, as seat 22moves in an arcuate fore-and-aft direction, as indicated by arrows 35.As shown in the drawings, pivot 30 is at uppermost portion of frame 23,but it will be appreciated that pivot 30 can be moved to a lowerposition (or a higher position if frame 23 is upwardly extended) withoutdeparting from the spirit and teaching of the present invention.

The moveable backrest mounting assembly of the present inventionenhances safety in front end impacts, but it is particularlyadvantageous in enhancing safety when the person's head is acceleratedrearwardly. For example, when the vehicle is subjected to a rear endimpact, or the person seated on the seat rebounds rearwardly on afrontal impact. The effect of mounting the lower end of the backrest formovement with the seat while keeping the upper end confined by thebackrest frame for near vertical displacement can be best seen byreference to FIG. 2. A person 10 is shown in solid lines seated on seatassembly 21 while assuming a posture for normal driving. In a front endimpact, as indicated by arrow 14, the person moves to a frontwardlydisplaced broken line position 10 a, at which point the upper body andhead are cushioned by airbag 51 and the upper body is restrained by seatbelt 53. Seat 22 moves to the forward broken line position shown in FIG.2, and lower backrest cushion 36 moves to the forward position alsoshown in broken lines in FIG. 2.

Upon a rear impact as indicated by force vector 15, the person movesback to the posture of intermittent broken or center line of numeral 10b, at which point the headrest 41 moves to the higher verticallydisplaced position shown by intermittent lead line 41, to better engagethe head, and backrest 25 moves to the most rearwardly position tosupport the user's back.

Thus, in the forward impact situation, coupling of backrest member 36 tomove with the seat at its lower end enables the seat to swing to anupward position so as to resist submarining, while having the backrestfollow the user's back for most of the deceleration of the person'sforward motion. The rise of the front of seat 22 about the center ofgravity of the person minimizes stress on the person during the highdeceleration of the mass of the person, and the backrest does notinhibit this highly desirable arcuate seat motion. Moreover, when seat22 is in the forward position, upwardly inclined, anti-submarining seatpan member 49 and cushion 48 cup or hold the person as decelerationoccurs.

In the rear impact situation, the seat and lower backrest portion againmoves about the center of mass of the person so as to minimize theperson's mass acceleration, and the backrest straightens up, raising theheadrest assembly 41 upwardly along arrow 88 to support the head as itmoves rearwardly against cushion 41. Again, lower portion 18 of thebackrest frame 23 and cushion 36 move with the seat and do not interferewith or inhibit arcuate motion of the seat about axis 60.

A person seated on fixed seats in a vehicle tends to relax and slideinto flexion curving the spine causing sagging of the lumbar curve andreduced back support. In the seat assembly of the present invention, theposition of the backrest relative to the position of the seat correctsthis deficiency. The lumbar support area comes closer to the lower backof the person as the seat cushion moves forward to significantlyincrease low back support as the angle between the seat and the backrestbecomes more acute.

When the seat rotates rearwardly voluntarily or under a rear end impact,the backrest and headrest move up closer to the shoulders and head, thusimproving support.

While the guided channels 29 in the illustrated embodiment are linear,it will be understood that motion of upper end of backrest frame 23 alsocould be guided for arcuate motion which is slightly concaved in aforward direction.

An important aspect for the proper functioning of a dynamic seat relatedto safety is the location of the center of rotation of the seat. Theseat's center of motion 60 most preferably is 34 mm above the center ofmass, CG, of the seated person. Numerous crash tests have establishedthat there will be a reduction in injury loads during the crash. Theseat of the present invention significantly contributes to the reductionof injury loads of about 30% to comply with federal standards testsFMVSS 208, 30 mph belted and unbelted; Offset Impact, 40 mph Belted; andUS-NCAP, 35 mph Belted. The dynamics provided by the enhanced protectionof the present seat assembly against frontal and rear impacts reducecrippling injuries and in some cases reduce the likelihood of afatality.

Another important feature of the present invention is that together withbackrest motion and seat/backrest deceleration function 76 shown in FIG.7 or 89 shown in FIG. 8 provides a shock absorber means for frontal orrear impacts.

The seat assembly of the present invention further preferably includes arecliner assembly, generally designated 33. FIG. 3 shows reclinerassembly 33 at what is preferably its full reclined limit, namelythirty-five degrees rearwardly of the position in FIGS. 1 and 2.Recliner mechanism 33, best seen in FIGS. 12 and 6, is coupled betweenupwardly and rearwardly extending arms of seat assembly mounting shellsupport means 26, and a back recliner frame 32 and 81, to which backrestchannels 29 or 78 in FIG. 6 are fixedly mounted, is provided which isseparate and apart from the movable backrest frame 23 and 82. Themechanism for selectively locking and releasing recliner frame 32 forreclining can take any one of a number of standard forms which allowselected tilting of backrest frame 23 rearwardly from its orientation inFIG. 2 to that of FIG. 3 or FIG. 6.

As shown in the drawing, member 33 a has an arcuate array of teeth 33 b.This rack or gear member 33 a is fixedly carried by the recliner frame.A pivotal arm 33 c having handle 33 d is mounted to stationary seatmounting shell 26. At least one interlocking member, such as pins 33 eare carried by end of arm 33 c and interengage with teeth 33 b. Arm 33 cmay be rotated upwardly about pivot 33 f to release pins 33 e from teeth33 b to allow motion of recliner frame 32 relative to mounting member 26about pivot 33 g. Link 33 h (FIG. 6) coupled to arm 33 i which is keyedto transverse axle 33 j transmit arm 33 c motion to the other side ofthe assembly to release the pins from rack or gear 33 a on the otherside of the seat.

FIG. 3 shows the preferred reclined angular geometry of the personseated on seat assembly 21 in the reclined position, but it will beunderstood that other angles can be provided for. When seat 22 is in aupwardly inclined position, 66 degrees from vertical as shown in FIG. 3,and the backrest 25 is reclined back from the vertical by 60 degrees,the included angle of 126 degrees between the torso and thighs isregarded as a neutral body posture whereas the muscular-skeletal systemis in equilibrium at rest (NSA-NBP). Sleeper posture is intended fortransportation uses such as aircraft seats. It will be noted in FIG. 3that seat cushion 48 is in the full, forward position with backrest 25and cushion 36 fully reclined to provide lumbar support for the user'sback in the reclined position.

The reclined position of FIG. 3 is much more effective in distributingthe weight of the user over the seat and seat back than is true forfixed seats which remain horizontal. When sitting on a horizontal fixedseat with a reclined back, the user's weight is concentrated on thebuttocks, and the thighs are lifted up off the seat losing support. Theuser tends to slide forwardly off the seat unless his or her buttocksdigs into the cushion. The lumbar curvature also loses support which isundesirable.

In the present seat assembly, the front edge of the seat rises up underthe thighs and the user's weight is more evenly supported over the areaof cushion 48. The backrest cushion 36 follows the seat and maintains adesirable forward thrust to the lumbar region.

Additionally, and very importantly, seat assembly 21 makes moreefficient use of space than simply reclining the seat backrest cushionassembly from proximate the rear of the seat. Thus, seat 48 movesforward, as does the back rest assembly during seat motion when thebackrest is reclined about pivot point 33 g. The headrest also islowered so that in an airline application, for example, the backrestdoes not invade the space of the seat behind to the same degree asoccurs for conventional reclinable seats.

FIGS. 6 and 7 illustrate an alternative embodiment of the seat assemblyin which a single backrest member or cushion 36 has been used, whichbackrest member extends up to the user's shoulders. Thus, upper backrestmember or cushion 39 of FIGS. 1 and 2 has been combined, in effect, withlower backrest member or cushion 36. A modified backrest frame 82 alsois provided. Frame 82 again is linked or coupled for movement with seat22 by a pair of pivots 47 and connected links 50, which are secured toseat pan 24, as above described. Frame 82 is mounted for verticallyextending movement, as indicated by arrows 97 by a pair of axles 30,which are welded at 96 to frame 82 somewhat above the middle of frame82. Axles 96 carry rollers or slider assemblies 79 that move up and downin guide channels 78. This allows the movable backrest frame 82 to beseparated from the tiltable recliner frame 81.

Channels 78 are fixed proximate a top end of a separate back reclinerframe 81. A cross beam 55 is provided at a lower end of frame 81 andrecliner mechanism 33 is secured to cross beam 55. This assembly fixesthe position of the slide plane formed by channels 78 relative tostationary seat assembly support structure 26. Thus, for any selectedrecliner frame angle, backrest frame 82 can move fore-and-aft with seat22 and its lower end and can slide or roll up and down along arrow 80 atits upper end.

The backrest of FIGS. 6 and 7 is designed to receive side bolsters fixedto movable backrest frame 82. A back cover, not shown for simplicity,also can be provided to hide intermediate back recliner frame 81. In theembodiment of FIGS. 6 and 7, headrest support member 40 is fixed tobackrest frame 82 and headrest cushion 41 moves with backrest cushion36, as best can be seen in FIG. 7.

FIG. 6 also discloses a height adjustment mechanism for seating assembly21. An electric motor 120 may be used to extend a rod 121, which rotateslink 122. Link 122 is secured to rotate axel 43, which, in turn, iscoupled to rotate height adjusting links 44. Pivot assemblies 45 attachlinks 44 to the seat assembly support structure 26. By extending orshortening rod 121, link 44 will rotate, as shown by direction arrow123. Support structure arm 26 also is caused to move forward and backalong direction arrow 124, which is supported on an inclined plane atthe frontal cross bean 42 by sliding means securing 26 to 42 with a boltand mating fore and aft slotted holes in a conventional manner (notshown). In this manner the seating assembly 21 can be adjusted up ordown.

The range of arcuate motion of seat 22 can be as much as 35 degrees in aforward direction and 20 degrees rearward. These limits can be alteredto meet the need of the seat's application.

As is typical in many automobiles and as is shown in FIGS. 5, 6 and 7, arestraint device, such as a shoulder belt 53, may be provided. Belt 53has an upper end 83 mounted over a roller assembly 95 and coupled toupper end of movable backrest frame 82, by a standard retractor and/orload limiter 127. A lap portion 53 a of belt 53 is secured at anchor 74to seat mounting structure 26 at a position located straight below theuser's hip joint, on the window side of seat 21. An opposite end of beltportion 53 a with standard buckle 120 is symmetrically anchored at theother side of seat 21. Pretension, retractors and load limiters 127 alsocan be installed at anchor points 74 and secured to the backrest frameassembly support structure 26, or on the floor structure, or a pillarprovided in the vehicle.

In addition, when belt anchors are located on the floor 45, lap belt 53a can be rerouted with a roller and pin, which provides a continuousloop anchor point located preferably straight under the hip-femur jointfixed at the location of anchor 74; in this manner the belt causes thebody to be pulled down into the seat during a crash event. Moretypically anchor points 74 would be located to the rear of the seat in afixed seat assembly so as to pull back on the user during a crash event.More typically anchor point 74 would be located to the rear of the seatin a fixed seat assembly so as to pull back on the user during a crashevent. In the present invention, having an arcuately movable seat,however, anchor 74 insures that the user is held down against the seatas the seat moves along its arcuate path. A rearwardly positioned anchorpoint for lap belt portion 53 a would resist seat arcuate motion but canalso be accomplished by using belt material that stretches with moreelongation to allow seat arcuate motion.

In FIG. 7, a ten degree range of self-adjustment motion is shown duringnormal driving conditions. Extending the legs by a voluntary change inposture can be used to produce rotation of the seat assembly. Thatrotation about axis 60, in turn, causes a change in the height andangular position of backrest 36, raising headrest 41 upwardly by about50 mm. When seat 22 rotates rearward, the backrest and headrest move upcurving in closer to support the head, as shown by arrows 80. In thisposition the occupant can easily rest his or her head on the headrest,and can easily reach a comfortable balance, while still having his orher eyes on the road. In this manner, the entire supporting cushionassembly can be adjusted between very upright and somewhat reclinedpostures, by just rotating the seat angle with voluntary motion of thelegs, buttocks or torso.

Meeting the goal of maintaining a stable body equilibrium involvespreventing backrest 36 from moving downward by weight. Maintaining adynamic equilibrium state can be assisted by motion controller 76 ofFIGS. 7 and 89 in FIG. 8. Motion controller 76 applies a force whichbiases seat 22 to balance the seat against the gravitational pull of theweight of the user's torso on the seat. Such biasing can be accomplishedby compression springs 76, coupled by attachment devices 77 at thefrontal edge of seat pan 24 and at floor mounting assembly 42, or at theseat support or mounting shell 26.

Although not shown, a biasing adjustment assembly also can be providedfor example, a cam that can regulate the spring force by graduallycompressing spring 76. The cam can be set at different positions toadjust the equilibrium point for different sized people. Biasing of seat22 rearwardly resists the tendency of the user to slouch or slide thehips forwardly.

Motion controller 76 can also take the form of a shock absorber (notshown) which causes resilient displacement of the buttock against theshock absorber when deceleration on the seat exceeds a know force (forexample, is greater than 2-5 kN).

Control device 76 also can take the form of a piston in a pressurecylinder with a pyrotechnic device having the ignition timing controlledby the vehicle's computer or other restraints deployment system. Thus,an electric solenoid can actuate or ignite the pyrotechnic device atcollision to boost or accelerate seat rotation and the compound backrestmotion.

Motion controller 76 can alternatively be controlled by the driverduring normal operation for comfort and control of the seat tilt motionby a manual switch or an on-board computer.

In FIG. 8, shows the seat assembly of the present invention mounted in avehicle such as a van or truck having in the front seat position ataller floor mounting suspension means 87. Suspension assembly 87 can beused in heavier vehicles to cushion road bumps or potholes. Rear seatposition in FIG. 8 shows the present seat assembly mounted to a deck 84having legs 86 supported and attached to vehicle floor 45.

When the vehicle is driven over a bump, the cab jumps up, moving theentire seating assembly 21 upwardly. Thus, the driver moves from thesolid line position 10 to the broken line position 10 a.

The lower end of backrest member 36 moves along an arcuate path, asshown by arrows 90, as the seat moves rearwardly along an arcuate path,and the upper end of cushion 36 moves upwardly, as shown by arrows 88.The driver's body remains aligned during this motion with the driver'sfoot on the floor or gas pedal.

Backrest biasing compression spring 89 provides a dynamic seat balancingforce and additional suspension function which may be applied betweenrecliner frame cross member 55, that is mounted to seat mountingstructure support means 26, and backrest frame 82, at approximately thelevel of axles 30. Spring 89 balances assembly 21 against downward bodymotion.

The total trajectory of the body, therefore, is influenced by twostructures. First, suspension 87, which displaces as indicated by arrows101, and second by the movement of the seat assembly of the presentinvention, which moves as indicated by arrows 88, 90 and 91. In thismanner, seat assembly 21 adjusts to support the body during changes inposture and/or during an occurrence of violent vertical or horizontalacceleration.

Although not shown, using a turning knob or motorized means to causeseat movement by selectively rotating the rollers elements 27 around itsaxis and thereby rotate seat track 28 to a new position can be utilized.

The seat assemblies of FIG. 8 are constructed substantially as describedin FIGS. 1-5. In addition to suspension 87 and floor mount 84, 86,rollers 27 guide arcuate motion of seat 22 on guide tracks 28 instead ofsliders. Moreover, backrest member 36 is a single member supported witha recliner frame 81 or 32 constructed as shown in FIGS. 1, 6, 7 and 10,and the back seat in FIG. 8 is mounted to a rear wall or panel 102 ofthe vehicle.

Turning now to FIGS. 9A-9C, an embodiment is shown in which arcuateguide tracks 140 were formed as separate members that are affixed byfasteners, welding or the like to seat pan 24 proximate the bottom ofside walls 24 a of the seat pan. Mounted to support guide tracks 140 arearcuate members 141, which are secured to mounting member 42. Arcuateseat tracks 140 are movably supported on arcuate members 141 by aplurality of ball or roller bearings 142, best seen in FIGS. 9B and 9C.

In addition to the guide track arrangement show, FIGS. 9A-9C illustratea seat releasable locking or detent assembly, generally designated 130,that will hold the tracks 140 in a fixed location on arcuate supports141 until an inertial threshold is exceeded, for example, in a frontalrapid deceleration of 2 gs.

In enlarged scale sectional views 9B and 9C show an inertialocking/release assembly 130 formed to include a vertically reciprocalpin 132 slidably mounted inside bushing or sleeve 134 and formed with apointed or tapered end 128 which is dimensioned to protrude throughselected ones of a plurality of holes or mating pockets 139. In FIG. 9Bpin 132 is shown retracted in the solid lines and cross-hatched and isshown with tapered end 128 in holes 139 in broken lines. Movement of pin132 between the solid line and broken line positions can be manuallyactivated by handle 131.

Handle 131 is used to turn shaft 137 inside busing 136, as indicated byrotation arrows 145 shown in FIG. 9C. Pin 132 is pushed up or down by afinger member 146 having a forked end which fits in a notch 103 in pin132. When handle 131 is rotated, shaft 137 rotates and finger 146 istilted. Finger 146 can be mounted through a transverse bore throughshaft 137 and held in place by a set screw 146 a. The outer end of finer146 can be formed with a cylindrical cup 135. Inside cylindrical cup 135a spring 143 biases ball 144 against the side of housing 138. In thismanner, when pin 132 is engaged in pockets 139, spring 143 is biasingfinger 146 upwards and, therefore, pin 132 against into pockets 139 oftrack 140. Although not shown, it can be used in curved track 28. Thedetent pin will remain biased upwardly locking seat 22 to support member141 on cross beam 42, the seat assembly support structure 26 is notshown for clarity.

Release of seat 22 for arcuate motion can occur in either a fore-or-aftdirection by acceleration of track 140 and seat 22, represented byvector arrows 104 in FIG. 9C. Thus, in frontal crashes or upon rear endimpacts as tracks 140 that define holes or pockets 139 push the inclinedface 128 of pin 132 fore or aft, pin 132 is displaced down to the solidline position in FIG. 9B or the broken line position of FIG. 9C. As ball144 passes over the center line of the tilt range of finger 146, spring143 biases the finger to the downward or pin retracted position.

Manual release of seat motion is accomplished by turning handle 131 in acounter clockwise direction to tilt finger 146 in a counterclockwisedirection in FIG. 9C and displace pin 132 to the lowered position.Cylindrical cup 135 is rotated upward, about 30 degrees along arrow 145,biasing pin 132 downward with sufficient clearance to displace end 128out of opening 139 in track 140, which releases the track and seat forarcuate movement.

FIGS. 10A and 10C are perspective views of three alternative embodimentsof the moveable backrest frame and the separate recliner frames of theseat assembly of the present invention.

FIG. 10A shows a one-piece movable backrest frame 150 that movesaccording to the present invention between relatively stationary sidebolsters 56, schematically shown. Bolster 56 are fixed to recliner frame32. In this manner side bolsters 56 and a backrest back cover, or seatbelts, not shown here for simplicity, can remain firmly attached torecliner mechanism 33 during motion of backrest frame 150.

FIG. 10B is a seat assembly having a two-piece, full width backrestframe assembly with a lower backrest frame portion 151 and an attachedupper backrest frame portion 152. A pivot pin 30 connects lower backrestframe 151 to slider member 31. Fixed to a connecting plate 153 is upperbackrest frame portion 152 that also is attached to slider 31 formovement therewith. Frame portion 152, therefore, moves up and downalong the line of mating guide channels 78. Channels 78 are, in turnstructurally fixed to separate recliner frame member 81. pivot assembly47 is linked y links, not shown, to the seat, as described in connectionwith FIGS. 1-5. Backrest frame 151.

FIG. 10C discloses a backrest assembly comprising a recliner framemember 81 with cross beam 55 proximate a bottom end thereof. Reclinermechanism 33 carries guide channels 78, which are structurally fixed tothe seat mounting assembly (not shown) as was described in connectionwith FIGS. 1-5. Connecting plate 153 couples upper backrest frameportion 152 to recliner frame 81. Pivot 47 is coupled by link (such aslink 50) to the seat pan so that frame 151 moves fore-and-aft in thearcuate path following the seat. An upper edge of backrest frame 151 isconnected by pivot 30 to rollers 79 for vertical movement as guided bysliding channels 78.

Coupled by pins 154 to an upper edge of the movable lumbar support framemember 151 are tubular members 155, that extend through bushing 156 andare fixed to upper backrest frame portion 152. Joining of bushing 156 tothe upper edge of frame neighbor 152 is preferably flexible to allow anymisalignment of member 155 due to arcuate seat motion. Headrest 41 iscarried by frame member 40 that is telescoped inside tubular members 155to enable adjustment of the height of the headrest. In this manner,upper backrest frame portion 152 remains fixed to recliner frame member81, and lumbar frame member 151 is formed to follow arcuate seat panmotion at the lower end and to reciprocate at the upper end.

FIG. 11 is an alternative embodiment of seat assembly 21 in the presentinvention in which lateral seat motion is implemented using sphericalsupport of the seat by the seat mounting assembly. Vehicles, of course,are subjected to lateral and/or of-set impacts which produce rapidacceleration of the vehicles' occupants. Thus, complex compound forcevectors can be applied to the vehicle which will not necessarily bealigned with the fore-and-aft seat motion of the embodiments of thepresent invention described above. The seat assembly of FIG. 1 isconstructed in a manner which enables seat movement that will at leastpartially accommodate or reduce the shock and vibration from lateraldiagonal and off-set (not axially aligned or directly head-on) crashes,as well as frontal and rear impacts.

In the embodiment of FIG. 11 guide tracks 161 having a spherical surfaceare provided on seat pan 24, while mating spherical support surfaces 162are provided on seat mounting structure 26. In the FIG. 11 embodimentsupport, surfaces 162 are connected by an intermediate surface 160 forstructural rigidity. Surface 160 is shown as a spherical surface too,but a cylindrical, arcuate or discontinuous reinforcing structure 160between spherical support surfaces also could be employed becausesurface 160 does not directly support tracks 161 or seat pan 24. Tracks161 are mated with support surfaces 162 for sliding contact therewithand tracks 161 and surfaces 162 preferably have substantially the sameradius of curvature 165 and axis rotation centered at point 60 that isgenerally proximate to the center of mass of the occupant. Seat 24 asshown will, therefore, be supported for movement in the fore-and-aftdirection, as shown by arrows 35, in a lateral direction, as shown byarrows 163, and in directions which are various combinations offore-and-aft and lateral directions.

As was the case for other embodiments of the present invention, movablebackrest frame 23 is coupled at a lower end to seat pan 24 for movementtherewith while upper end 99 is coupled to separate recliner frame 32 at30 for vertical reciprocation in response to seat movement. Since seatpan 24 can move along a spherical path, it is preferable that link 50 becoupled to backrest frame 23 by spherical coupling rather than a merepivotal coupling 47. A spherical coupling at point 47 will reduce thetendency to twist backrest frame 23 in a manner sufficient tosignificantly impede spherical seat movement under lateral impact forcevectors, such as vectors 170. Some resilient frame twisting can beexperienced without materially affecting the seat's performance and somedifference in height of pivots 30 at each side will also accommodate andrelive said frame twisting.

The advantage intended by the embodiment of FIG. 11 is to reduce injurycausing forces and to improve safety during an offset frontal crash,such as proposed by NHTSA, and/or a side impact crash. In addition, whenapplied to an off road vehicles or industrial equipment such as atractor, seat assembly 21 of FIG. 11 will act as a lateral suspension toreduce the health hazards of constant pitching and rolling.

The movable backrest framework assembly of the present invention alsocan be employed with seat mounting structures which only approximate acontinuous one radius are about a center of curvature proximate theuser's center of gravity. Thus, in FIGS. 12A and 12B two alternativeseat mounting structures are illustrated with the movable backrestassembly of the present invention.

In FIG. 12A, arcuate fore-and-aft motion 35 of seat 22 is obtained bythe use of pairs of pivoted arms or links. A front pair of arms or links175 and a rear pair of rear links 176 are provided that pivot about axleassemblies 177 and 178. Axles or pivots 177 are mounted to floormounting rails 40 or to assembly mounting means 26 while upper axles orpivots 178 are mounted to seat pan 24. Links 175 and 176 rotate aboutpath 179 in the front and about a path 180 in the rear. In this manner,even though the path of motion of the links is a downward arcuate pathabout the axes 177, seat 22 is caused to move along an upwardly tiltingpath 35 that has an approximate axis of rotation 60 located proximatecenter of mass of an occupant seated on seat 22. The upper surface ofseat 22, therefore, moves along an arc that is centered about axisrotation 60. As above described in connection with other embodiments,backrest member 36 is coupled to seat pan 24 by a link 50 and a pivotassembly 47.

In FIG. 12B, guide slots 184 and 185 are provided in seat assemblymounting structure 26, and the slots are formed to allow rolling orsliding elements 186 and 189 to travel along paths of motion indicatedby arrows 188 and 190. Seat pan 24 is attached to the front rollingelement 189 by triangular member 200 and directly to rear rollingelement 186 by an axle mounting busing not shown. The rear of the seatpan will travel downward along guide 184 while the front of the seatwill travel predominately forward and upward along guide 185. In thismanner, the surface of seat 22 will move substantially along an arc thatis centered at about axis 60.

Again, the motion of backrest cushion 36 will follow seat motion at itslower end by reason of links 50 and pivots 47. The upper end of backrestcushion 36 is pivoted at 30 to slider 31, as shown by arrow 98. In thismanner the combined seat and backrest motion of the present inventioncan be carried out with alternate seat pan motion mechanisms.

1. A seat assembly comprising; (a) a seat; (b) a seat mounting assemblymounting the seat in a near horizontal orientation for movement along anupwardly concaved arcuate seat path having one center of curvature abovethe seat and forward a backrest assembly; and (c) the backrest assemblyincluding a backrest member extending in a near vertical orientationproximate the seat mounting assembly, the backrest member having anupper backrest portion thereof mounted to the backrest assembly formovement in a vertically extending direction and having a lower backrestportion coupled for movement with the seat; wherein, the backrestassembly further includes a recliner frame and the backrest memberincludes a backrest frame movably mounted to the recliner frame, and therecliner frame is tiltably mounted to the seat mounting assembly.
 2. Theseat assembly as defined in claim 1 wherein, the backrest member isprovided by a first backrest member formed and positioned to support theuser's lumbar region and a second backrest member mounted above thefirst backrest member, the second backrest member being formed andpositioned to support the user's upper back, and the second backrestmember being mounted to an upper portion of the first backrest memberfor vertical movement therewith.
 3. The seat assembly as defined inclaim 2, and a headrest member carried by one of the first backrestmember and the second backrest member for movement therewith, theheadrest being formed and positioned for support of the user's head. 4.The seat assembly as defined in claim 1 wherein the seat mountingassembly includes guide tracks carried by one of the seat and a seatsupport structure, and a plurality of movable members carried by theother of the seat and the seat support structure and formed for movementrelative to the guide tracks.
 5. The seat assembly as defined in claim 4wherein, the guide tracks are arcuate and extend over substantially thefull fore and aft dimension of the seat.
 6. The seat assembly as definedin claim 1 wherein, the seat mounting assembly mounts the seat formovement along an upwardly concaved spherical path having a center ofmovement proximate the center of mass of a person seated on the seat. 7.The seat assembly as defined in claim 6 wherein, the backrest is coupledat a lower portion thereof for movement with the seat along thespherical path.
 8. The seat assembly as defined in claim 1 wherein, saidseat is coupled to the backrest assembly by a seat-femur length andlumbar depth adjustment assembly.
 9. The seat assembly as defined inclaim 8 wherein, the seat-femur length and lumbar depth adjustmentassembly includes a lumbar adjustment member slidably mounted to theseat and coupled to the backrest assembly, and a rotatable adjustmentdevice coupled to displace lumbar adjustment member in a fore-and-aftdirection to thereby adjust the distance from the front edge of the seatto the lower portion lumbar region of the backrest frame.
 10. The seatassembly as defined in claim 9 wherein, the lumbar adjustment member isa bar having a plurality of teeth formed therein, and the rotatableadjustment device is a rotatable axle mounted by bushings to the seatand having at least one slot therein formed to and receiving one of theteeth therein and having a manually engageable knob provided thereon.11. The seat assembly as defined in claim 1 wherein, the seat mountingassembly includes a seat locking assembly formed for selective lockingof the seat in and releasing the locked seat from a desired fore-and-aftposition opposite sides of the backrest.
 12. The seat assembly as defiedin claim 11 wherein, the seat locking assembly includes a frictionmember having a coefficient of friction selected to lock the seat in thedesired fore-and-aft position during normal use of the seat and to allowseat arcuate motion in a crash event.
 13. The seat assembly as definedin claim 12 wherein, the friction member is provided by a pad: a springbiasing member formed to bias the pad relative to the set mountingassembly toward engagement with a portion of the seat; a cam mounted tothe seat mounting assembly and formed to urge the pad away fromengagement with the seat in opposition to the spring biasing member; anda cam actuator formed and coupled for selective operations by the userof the seat assembly.
 14. The seat assembly as defined in claim 13wherein, the cam actuator is provided by a rotatable mounted rodcarrying the cam and having a manually engageable handle thereon. 15.The seat assembly as defined in claim 1 wherein, the seat mountingassembly includes a height adjustment mechanism formed to selectivelyraise and lower the height at which the seat is supported for arcuatemovement.
 16. The seat assembly as defined in claim 15 wherein, theheight adjustment mechanism is provided by an actuator coupled todisplace a height adjusting link acting on the seat assembly supportstructure.
 17. The seat assembly as defined in claim 1 wherein, the seatmounting assembly includes an inertia locking assembly formed toselectively lock the seat against arcuate motion and release the seatfor arcuate motion when a predetermined inertia level has been exceeded.18. The seat assembly as defined in claim 1 wherein, the seat includesan upwardly concaved seat pan with an anti-submarine member extendingtransversely across the seat.
 19. A seat assembly comprising: (a) aseat; (b) a seat mounting assembly mounting the seat in a nearhorizontal orientation for movement along an upwardly concaved arcuateseat path having a center of curvature above the seat and forward abackrest assembly; and (c) the backrest assembly including a backrestextending in a near vertical orientation, the backrest including a lowerbackrest member having a lower lumbar portion coupled for movement tothe seat, an upper lumbar portion coupled for guided movement to aremainder of the backrest assembly, and an upper backrest member mountedabove the lower backrest member, the upper backrest member being movablymounted to the remainder of the backrest assembly and coupled to thelower backrest for movement therewith, wherein the backrest furtherincludes a recliner frame and the backrest member includes a backrestframe movably mounted to the recliner frame, and the recliner frame istiltably mounted to the seat mounting assembly.
 20. A seat assembly asdefined in claim 19, and a headrest coupled to said upper backrestmember for movement therewith.
 21. The seat assembly as defined in claim19, wherein, the lower backrest member is pivotally coupled to the seatand pivotally coupled to the backrest assembly for vertical displacementof the backrest member during arcuate movement of the seat.
 22. The seatassembly as defined in claim 21, and a pair of vertically extending sidebolsters members mounted in a stationary manner to the seat mountingassembly on opposite sides of the backrest member.
 23. The seat assemblyas defined in claim 19 wherein the backrest assembly includes a reclinermechanism formed for selective rearward tilting of the recliner frame,the backrest member being moveable mounted to the recliner frame andbeing tiltable with the recliner frame.
 24. The seat assembly as definedin claim 23 wherein, the backrest frame is mounted to the recliner frameby a pair of vertically extending guide channels and movable membersmounted to the channels.
 25. The seat assembly as defined in claim 24wherein the movable members are one of slider members and rollermembers.
 26. The seat assembly as defined in claim 24 wherein, thechannels are carried by one of the backrest frame and recliner frame,and the movable members are carried by the other.
 27. The seat assemblyas defined in claim 24 wherein, the guide channels positioned laterallyoutwardly of the lower backrest member, and the guide channels extendvertically along opposite sides of the lower backrest member.
 28. Theseat assembly as defined in claim 27 wherein, the upper backrest memberis coupled for movement relative to the guide channels above the lowerbackrest member.
 29. A seat assembly as defined in claim 19 wherein, thelower backrest member is pivotally coupled to the seat and pivotallycoupled to the backrest assembly for vertical displacement duringarcuate movement of the seat, and the upper backrest member is fixed tothe recliner frame, and a headrest coupled to the lower backrest memberfor movement therewith.
 30. The inventions as defined in claim 19 andthe step of using a turning knob or motorized means to cause saidmovement by selectively rotating the rollers elements around its axisand thereby rotate the seat position.
 31. The seat assembly as definedin claim 19 wherein, the seat mounting assembly mounts the seat formovement along an upwardly concaved spherical path having a center ofcurvation proximate a person's center of mass when seated on the seat.32. A method of providing a seat assembly comprising the steps of;mounting a seat in a near horizontal orientation for movement along anupwardly concaved arcuate path having a center of curvature above theseat and forward a backrest: mounting the backrest in a near verticalorientation proximate the seat for support of the back of a user whileseated on the seat; and coupling a lower portion of the backrest to theseat for movement of the lower portion of the backrest with movement ofthe seat; and mounting an upper portion of the backrest for verticallyextending movement in response to movement of the lower portion of thebackrest wherein the step of mounting the backrest is accomplished bymounting the backrest to a recliner frame formed to support saidmovement of the lower portion of the backrest to position the backrestmember by the user and having a mechanism formed for selective recliningof the position of the backrest by the user.
 33. The method as definedin claim 32 wherein, the step of mounting the backrest is accomplishedby mounting the backrest for movement to a recliner frame coupled to thebackrest by guiding channels and mating sliding-roller elements mountedin the backrest assembly.